查看数据库连接数、死锁

1. 查看数据库连接数

1.1 命令查看

在命令窗口输入：

show parameter processes
show parameter session

1.2 sql查询

select count(*) from v$process;
select count(*) from v$session;

2. 死锁

2.1 检查是否存在死锁

select sess.sid,
       sess.serial#,
       lo.oracle_username,
       lo.os_user_name,
       ao.object_name,
       lo.locked_mode
  from v$locked_object lo, dba_objects ao, v$session sess
 where ao.object_id = lo.object_id
   and lo.session_id = sess.sid;

2.2 检查死锁的sql

select sql_text
  from v$sql
 where hash_value in
       (select sql_hash_value
          from v$session
         where sid in (select session_id from v$locked_object));

2.3 检查死锁用户和sql

select b.username, b.serial#, d.id1, a.sql_text
  from v$lock d, v$session b, v$sqltext a
 where b.lockwait = d.kaddr
   and a.address = b.sql_address
   and a.hash_value = b.sql_hash_value;

2.4 检查死锁用户和程序

select username, lockwait, status, machine, program
  from v$session
 where sid in (select session_id from v$locked_object);